We studied the effects of herpes virus carrier status on peripheral blood T lymphocyte subsets in 334 healthy individuals. IgG-class antibodies against cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV), and varicella-zoster virus (VZV) were used as markers for the carrier status of those viruses. CMV carrier status was associated with significant increases in the numbers of some T cell subsets, whereas the carrier status of EBV, HSV, and VZV had no significant effects. The 159 CMV-seropositive individuals had higher numbers of HNK1+ T cells than did the 175 CMV-seronegative individuals [mean (SD), 292 (196)/microL v 164 (89)/microL, respectively], including the CD4+HNK1+ T cells [38 (48)/microL v 9 (13)/microL, respectively] and the CD8+HNK1+ T cells [166 (146)/microL v 73 (54)/microL, respectively]. Morphological and cytochemical studies showed that the expression of HNK1 by the CD4+ and CD8+ T cells was associated with the occurrence of azurophilic cytoplasmatic granules and a loss of nonspecific esterase activity. The numbers of CD4+HNK1+ and CD8+HNK1+ T cells increased proportionally to the levels of the IgG- class CMV antibody titers. We suggest that the increased numbers of CD4+HNK1+ and CD8+HNK1+ granular T cells in CMV carriers reflect the persistent interaction between CMV and the immune system of its hosts.

Acute graft-versus-host disease (GVHD), a major complication of allogeneic bone marrow transplantation (BMT), is probably mediated by T lymphocytes present in the marrow graft. In this study, the repopulation of the peripheral blood with T4+ and T8+ T cells was investigated during the period preceding the occurrence of acute GVHD. Twenty-four allogeneic and 11 autologous BMT recipients were monitored from day 4 post-BMT onward by the use of monoclonal antibodies, indirect immunofluorescence, and flow cytometry. The recipients of allogeneic transplants received methotrexate as GVHD prophylaxis. Similar recovery patterns for T4+ and T8+ T cells were found following autologous and allogeneic BMT. However, lymphoid repopulation occurred at a clearly faster rate after autologous BMT. T4+ T cells were the first to reappear in the peripheral blood, followed by T8+ T cells 4–7 days later. The T8+ T cell reconstitution occurred at an even faster rate in patients who were to develop grade II-IV GVHD, as compared with those with grade O-I GVHD, thus leading to an earlier decrease in the T4/T8 ratio. Of 10 patients with a T4/T8 ratio less than 2.5 at day 19, 9 developed grade II-IV GVHD and 1 showed no GVHD. Of 14 patients with a ratio greater than 2.5 at that time, only 2 developed grade II-IV and 12 grade O-I GVHD (p less than 0.001). In the 11 patients developing grade II-IV GVHD, the T4/T8 ratio decreased to values less than 2.5 before the first clinical symptoms of GVHD in 9; it coincided in one and occurred later in another patient. Thus, early monitoring of the T4/T8 ratio can distinguish patients at risk of developing grade II-IV GVHD.

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